INTRODUCTION OF THE MICROSCOPE 8l 



he began to use tlie microscope is not known; his first pub- 

 lication in reference to microscopic objects did not appear 

 till 1673, when he was forty-one years old. 



His Microscopes. — He gave good descriptions and draw- 

 ings of his instruments, and those still in existence have been 

 described by Carpenter and others, and in consequence we 

 have a very good idea of his working equipment. During 

 his lifetime he sent as a present to the Royal Society of 

 London twenty-six microscopes, each provided with an object 

 to examine. Unfortunately, these were removed from the 

 rooms of the society and lost during the eighteenth century. 

 His lenses v;ere of fine ciuality and were ground by himself. 

 They were nearly all simple lenses, of small size but con- 

 siderable curvature, and needed to be brought close to the 

 object examined. He had different microscopes for different 

 purposes, giving a range of magnifying povrers from 40 to 270 

 diameters and possibly higher. The number of his lenses is 

 surprising; he possessed not less than 247 complete micro- 

 scopes, two of which were provided with double lenses, and 

 one with a triplet. In addition to the above, he had 172 

 lenses set between plates of metal, which give a total of 419 

 lenses used by him in his observations. Three were of 

 quartz, or rock crystal; the rest were of glass. More than 

 one-half the lenses were mounted in silver; three were in 

 gold. 



It is to be understood that all his microscopes were of 

 simple construction; no tubes,- no mirror; simple pieces 

 of metal to hold the magnifying-glass and the objects to 

 be examined, with screws to adjust the position and the 

 focus. 



The three aspects of one of Leeuwenhoek's microscopes 



shown in Fig. 19 will give a very good idea of how they were 



constructed. These pictures represent the actual size of 



the instrument. The photographs were made by Professor 



6 



